Modular endograft devices and associated systems and methods

ABSTRACT

Modular endograft devices and associated systems and methods are disclosed herein. In several embodiments, an endograft system can include a first endograft device and a second endograft device that each include an integrated frame, a cover and a lumen within the cover. Each endograft device further includes a superior portion and an inferior portion. The superior portion can have a convexly curved outer wall and a septal wall. The first and second endograft devices can be configured to extend into a low-profile configuration with a first cross-sectional dimension and a first length and self-expand into an expanded configuration with a second cross-sectional dimension greater than the first cross-sectional dimension and a second length less than the first length. In the expanded configuration, the septal walls can press against each other and form a septum between the lumens of the first and second endograft devices.

CROSS-REFERENCE TO RELATED APPLICATIONS

The present application claims priority to each of the following U.S.Provisional Applications:

(A) U.S. Provisional Application No. 61/265,713, filed on Dec. 1, 2009,entitled “IMPROVED SYSTEMS AND METHODS FOR MODULAR ABDOMINAL AORTICANEURYSM GRAFT;” and

(B) U.S. Provisional Application No. 61/293,581, filed Jan. 11, 2010,entitled “IMPROVED SYSTEMS AND METHODS FOR MODULAR ABDOMINAL AORTICANEURYSM GRAFT.”

All of the foregoing applications are incorporated herein by referencein their entireties.

TECHNICAL FIELD

The present technology generally relates to endograft devices andmethods for percutaneous endovascular delivery of the endograft devicesacross aneurysms. In particular, several embodiments are directed towarda modular bi-luminal endograft device with independently positionedcomponents for endovascular aneurysm repair.

BACKGROUND

An aneurysm is a dilation of a blood vessel at least 1.5 times above itsnormal diameter. The dilated vessel can form a bulge known as ananeurysmal sac that can weaken vessel walls and eventually rupture.Aneurysms are most common in the arteries at the base of the brain(i.e., the Circle of Willis) and in the largest artery in the humanbody, the aorta. The abdominal aorta, spanning from the diaphragm to theaortoiliac bifurcation, is the most common site for aortic aneurysms.The frequency of abdominal aortic aneurysms (“AAAs”) results at least inpart from decreased levels of elastins in the arterial walls of theabdominal aorta and increased pressure due to limited transverse bloodflow.

Aneurysms are often repaired using open surgical procedures. Surgicalmethods for repairing AAAs, for example, require opening the abdominalregion from the breast bone to the pelvic bone, clamping the aorta tocontrol bleeding, dissecting the aorta to remove the aneurysmal section,and attaching a prosthetic graft to replace the diseased artery. Therisks related to general anesthesia, bleeding, and infection in thesetypes of open surgical repairs result in a high possibility of operativemortality. Thus, surgical repair is not a viable option for manypatients. Moreover, the recovery process is extensive for the patientsfit for surgical repair. An open surgical repair of an AAA generallyrequires seven days of post-operational hospitalization and, foruncomplicated operations, at least six to eight weeks of recovery time.Thus, it is a highly invasive and expensive procedure.

Minimally invasive surgical techniques that implant prosthetic graftsacross aneurysmal regions of the aorta have been developed as analternative or improvement to open surgery. Endovascular aortic repairs(“EVAR”), for example, generally require accessing an artery (e.g., thefemoral artery) percutaneously or through surgical cut down, introducingguidewires into the artery, loading an endograft device into a catheter,and inserting the loaded catheter in the artery. With the aid of imagingsystems (e.g., X-rays), the endograft device can be guided through thearteries and deployed from a distal opening of the catheter at aposition superior to the aneurysm. From there, the endograft device canbe deployed across the aneurysm such that blood flows through theendograft device and bypasses the aneurysm.

EVAR devices should be implanted at a precise location across theaneurysmal region and securely fixed to the vessel wall because improperplacement, migration, and/or projection of the endograft device intobranching vessels may interfere with the blood flow to nearbyphysiological structures. For example, to avoid impairing renalfunctions, the endograft device should not inhibit blood flow to therenal arteries. In addition to the variations in the vasculature betweenpatients, the characteristics of the aneurysms themselves can also posechallenges because of the anatomical variations and the differentstructural features of individual aneurysms. For example, the vascularbifurcation at the iliac arteries and the angulation of aneurysmal sacsare both known to pose challenges to methods and devices for treatingAAAs. Conventional systems address these challenges by having manydifferent EVAR devices with different sizes and shapes.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1A is a partial cut-away, isometric view of a modular endograftsystem configured in accordance with an embodiment of the technology.

FIG. 1B is an isometric view of the modular endograft system of FIG. 1Aconfigured in accordance with an embodiment of the technology.

FIGS. 2A-C are cross-sectional top views of superior portions forendograft devices shaped in accordance with embodiments of thetechnology.

FIGS. 2D and 2E are cross-sectional top views of the superior portion ofFIG. 2B being mated with a complementary superior portion in accordancewith an embodiment of the technology.

FIGS. 3A and 3B are isometric views of endograft devices configured inaccordance with embodiments of the technology.

FIGS. 4A and 4B are side views of an integrated frame in an expandedconfiguration and in a low-profile configuration, respectively, inaccordance with an embodiment of the technology.

FIGS. 5A-C are side views of a cover being extended from an expandedconfiguration to a low-profile configuration in accordance with anembodiment of the technology.

FIGS. 6A and 6B are cross-sectional views of an endograft device in alow-profile configuration and in an expanded configuration,respectively, in accordance with embodiments of the technology.

FIGS. 7A and 7B are isometric views of endograft devices configured inaccordance with other embodiments of the technology.

FIGS. 8A and 8B are isometric views of endograft devices configured inaccordance with further embodiments of the technology.

FIGS. 9A and 9B are schematic views of a two-part modular endograftsystem being deployed across an aneurysm in accordance with anembodiment of the technology.

FIGS. 10A and 10B are isometric views of modular endograft systemsconfigured in accordance with additional embodiments of the technology.

FIGS. 11A and 11B are schematic views of the modular endograft system ofFIG. 10A and the modular endograft system of FIG. 10B, respectively,deployed across aneurysms in accordance with other embodiments of thetechnology.

FIG. 12 is a schematic view of the modular endograft system of FIG. 9Bdeployed across an aneurysm in accordance with a further embodiment ofthe technology.

FIGS. 13A-C are schematic views of a four-part modular endograft systembeing deployed across an aneurysm in accordance with an embodiment ofthe technology.

FIGS. 14A and 14B are isometric views of a modular endograft systemconfigured in accordance with an additional embodiment of thetechnology.

FIGS. 15A and 15B are schematic views of a three-part modular endograftsystem being deployed across an aneurysm in accordance with anembodiment of the technology.

FIG. 16 is a schematic view of a five-part modular endograft systembeing deployed across an aneurysm in accordance with an embodiment ofthe technology.

FIGS. 17A-E are views of coating layers being applied to an integratedframe in accordance with an embodiment of the technology.

DETAILED DESCRIPTION

Specific details of several embodiments of the technology are describedbelow with reference to FIGS. 1A-17E. Although many of the embodimentsare described below with respect to devices that at least partiallyrepair abdominal aortic aneurysms (“AAAs”), other applications and otherembodiments are within the scope of the technology. For example, thetechnology can be used to repair aneurysms in other portions of thevasculature. Additionally, several other embodiments of the technologycan have different configurations, components, or procedures than thosedescribed in this section. A person of ordinary skill in the art,therefore, will accordingly understand that the technology may haveother embodiments with additional elements, or the technology may haveother embodiments without several of the features shown and describedbelow with reference to FIGS. 1A-17E.

With regard the use of “superior” and “inferior” within thisapplication, inferior generally refers being situated below or directeddownward, and superior generally refers to being situated above ordirected upward.

With regard to the use of “expansion” and “constriction” within thisapplication, expansion refers to a radial increase in a cross-sectionaldimension of a device or component, and constriction refers to a radialdecrease in the cross-sectional dimension of the device or component.For example, FIG. 4A shows an integrated frame 104 in an expandedconfiguration, and FIG. 4B shows the integrated frame 104 in aconstricted configuration.

With regard to the use of “contraction” and “extension” within thisapplication, contraction refers to a longitudinal decrease in the lengthof a device or component, and extension refers to a longitudinalincrease in the length of the device or component. For example, FIG. 5Ashows a cover 106 in a contracted configuration, and FIG. 5C shows thecover 106 in an extended configuration.

With regard to the terms “distal” and “proximal” within thisapplication, the terms can reference a relative position of the portionsof an implantable device and/or a delivery device with reference to anoperator. Proximal refers to a position closer to the operator of thedevice, and distal refers to a position that is more distant from theoperator of the device.

1. Endograft System Structures

1.1 Selected Endograft Devices

FIGS. 1A and 1B are isometric views of a modular endograft system 100(“system 100”) in accordance with an embodiment of the technology. Thesystem 100 can include separate endograft devices 102 (identifiedindividually as a first endograft device 102 a and a second endograftdevice 102 b) that can be coupled, mated, or otherwise substantiallysealed together in situ. Each endograft device 102, for example, caninclude an integrated frame 104 (“frame 104”) and a substantiallyimpermeable cover 106 (“cover 106”) extending over at least a portion ofthe frame 104. The frame 104 and the cover 106 of an individualendograft device 102 can form a discrete lumen 116 through which bloodcan flow to bypass an aneurysm. In operation, the endograft devices 102are generally delivered separately and positioned independently acrossthe aneurysm.

As shown in FIGS. 1A and 1B, each endograft device 102 includes asuperior portion 108 and an inferior portion 110. The superior portion108 can include a convexly curved outer wall 112 and a septal wall 114.As shown in FIG. 1A, the septal wall 114 can be substantially flat suchthat the superior portion 108 forms a “D” shape at a superior portion ofthe lumen 116. In other embodiments, the septal wall 114 can be convexlycurved with a larger radius of curvature than the outer wall 112 suchthat the superior portion 108 forms a complex ellipsoid having anotherD-shaped cross-section at the superior portion of the lumen 116. Infurther embodiments, the superior portion 108 can have asymmetricalshapes or other suitable cross-sectional configurations that can matewith each other in the septal region and mate with an arterial wallaround the periphery of the outer wall 112. The inferior portion 110 canhave a circular cross-sectional shape as illustrated in FIG. 1A, or theinferior portion 110 can have an elliptical shape, a rectangular shape,an asymmetrical shape, and/or another suitable cross-sectional shape foran inferior portion of the lumen 116.

The superior portions 108 of the endograft devices 102 are matedtogether and at least substantially sealed along the septal walls 114within the aorta above the aneurysm. In some embodiments, the superiorportion 108 can be approximately 2-4 cm in length to adequately fix theouter walls 112 to the arterial walls such that they are at leastsubstantially sealed together. In other embodiments, the superiorportion 108 can be longer or shorter. In one embodiment in accordancewith the technology, the inferior portions 110 can extend through aninferior portion of the aneurysm and into corresponding iliac arteriesto bypass the aneurysm. In another embodiment, one or both inferiorportions 110 can terminate within the aneurysm to form what is known tothose skilled in the art as a “gate.” As described in further detailbelow, limbs (not shown) can be attached to the proximal ends of theinferior portions 110 and extended into the iliac arteries to bypass theaneurysm.

In the embodiment shown in FIGS. 1A and 1B, the frames 104 have bare endportions 118 (identified individually as first end portions 118 a andsecond end portions 118 b) that extend beyond the covers 106. As shownin FIGS. 1A and 1B, the first end portion 118 a can extend distally fromthe superior terminus of the cover 106, and the second end portion 118 bcan extend proximally from the inferior terminus of the cover 106. Insome embodiments, the end portions 118 can be trumpeted or flared tointerface with the arterial walls of the aorta and/or the iliacarteries. This can promote cell ingrowth that strengthens the sealbetween the endograft devices 102 and the adjacent arteries.

The end portions 118 can also increase the available structure forsecuring the endograft device 102 to the artery and increase the surfacearea of the covers 106 for sealably fixing the endograft devices 102 toarterial walls. This decreases the precision necessary to position theendograft devices 102 and increases the reliability of the implantedsystem 100. For example, a short infrarenal aortic neck (e.g., less than2 cm) generally requires precise placement of the endograft devices 102to preserve blood flow to the renal arteries while still providingenough surface area for the endograft devices 102 to be properly affixedwith the aorta. In the embodiment shown in FIGS. 1A and 1B, however, thefirst end portions 118 a can be placed at the entrance of the renalarteries to allow lateral blood flow into the renal arteries and providea larger structure for fixing the endograft devices 102 to the arterialwall and a larger sealing area with the arterial wall. The end portions118 can also provide accessible sites for recapture (e.g., byguidewires, bead and collet, etc.) that enhance the accuracy ofpositioning the endograft devices 102 across the aneurysm.

During deployment of the system 100, each endograft device 102 can bedelivered independently to an aneurysmal region in a low-profileconfiguration. The low-profile configuration has a first cross-sectionaldimension and a first length that can facilitate percutaneousendovascular delivery of the system 100. Because each device 102 extendsaround only a portion of the vessel periphery, the individual endograftdevices 102 can be constricted (i.e., radially collapsed) to a smallerdiameter than conventional AAA devices with a single superior portionthat extends around the complete periphery of the vessel wall. In someembodiments, for example, each of the endograft devices 102 can have adiameter of 25 mm in the expanded configuration, and can be constrictedto a diameter of 4 mm in the low-profile configuration to bepercutaneously deployed across the aneurysm through a 12 F catheter.Additionally, as described in more detail below, because each endograftdevice 102 is delivered independently, the end portions 118 andfenestrations can facilitate staggering the endograft devices 102 toaccommodate asymmetrical anatomies.

At a target site in the aneurysmal region, the endograft devices 102 canself-expand to an expanded configuration (e.g., shown in FIGS. 1A and1B). The expanded configuration can have a second cross-sectionaldimension greater than the first cross-sectional dimension and a secondlength less than the first length. In the expanded configuration shownin FIG. 1B, the septal wall 114 (FIG. 1A) of the first endograft device102 a can be forced against the opposing septal wall 114 of the secondendograft device 102 b. When in situ within the aorta, the forcesbetween the opposing septal walls 114 form a septum 120 in which thefirst and second septal walls 114 are at least substantially sealedtogether to prevent blood from flowing between the endograft devices 102and into the aneurysm. Additionally, as shown in FIG. 1B, the texture(e.g., ribbing) on the covers 106 can mate at the septum 120 to furtherstrengthen the seal between the septal walls 114. Similarly, the textureof the cover 106 on the outer walls 112 can interface with the adjacentvessel walls to strengthen the seal around the periphery of theendograft devices 102.

In operation, the system 100 can prevent blood from collecting in adiseased aneurysmal portion of a blood vessel (e.g., the aorta, theiliac arteries, etc.). Rather, the system 100 can direct blood into thelumens 116, funnel the blood through the superior and inferior portions108 and 110, and discharge the blood into healthy portions of the iliacarteries, thereby at least substantially bypassing the aneurysm. Thebifurcated system 100 facilitates independent positioning of the firstand second endograft devices 102 to accommodate disparate structures andmorphologies of the abdominal aorta and/or iliac arteries. For example,the first endograft device 102 a can be positioned independently in adesired location without being constrained by a desired placement of thesecond endograft device 102 b. Accordingly, the system 100 can easilyadapt to a variety of different anatomies and thereby provide a modularalternative to customized endograft systems.

1.2 Select Embodiments of Superior Portions

FIGS. 2A-C are cross-sectional top views of superior portions 208 ofendograft devices (e.g., endograft devices 102 shown in FIGS. 1A and 1B)shaped in accordance with embodiments of the technology. The superiorportions 208 can have generally similar features as the superiorportions 108 shown in FIGS. 1A and 1B. For example, each superiorportion 208 includes an outer wall 212 and a septal wall 214. The outerwall 212 is generally semi-circular, but can otherwise be configuredaccording to the shape, geometry, and/or morphology of an arterial wall.The septal wall 214 can be shaped to mate with a complementary septalwall 214 of another endograft device. More specifically, in theembodiment illustrated in FIG. 2A, the superior portion 208 includes aconvexly curved, substantially semi-circular outer wall 212 and asubstantially flat septal wall 214. Thus, the superior portion 208 formsa “D” shape and can be part of a system (e.g., the system 100 shown inFIGS. 1A and 1B) including a corresponding D-shaped superior portion ofa mating endograft device.

In other embodiments, both the outer wall 212 and the septal wall 214can be convexly curved such that the superior portion 208 forms acomplex ellipsoid with at least two distinct radii. FIG. 2B, forexample, shows the superior portion 208 can include a convexly curvedouter wall 212 that has a first radius R1 and a convexly curved septalwall 214 that has a second radius R2 greater than the first radius R1.In the embodiment illustrated in FIG. 2B, the second radius R2 issubstantially greater than the first radius R1 such that the superiorportion 208 has a substantially D-like shape.

Similarly, the superior portion 208 shown in FIG. 2C includes theconvexly curved outer wall 212 that has the first radius of curvature R1and the convexly curved septal wall 214 that has the second radius ofcurvature R2 greater than the first radius R1. As shown in FIG. 2C, thesuperior portion 208 can further include convexly curved corner sections222 (identified individually as a first corner section 222 a and asecond corner section 222 b). The first corner section 222 a can have athird radius R3, and the second corner section 222 b can have a fourthradius R4 distinct from or equivalent to the third radius R3. In theembodiment shown in FIG. 2C, the third and fourth radii R3 and R4 aresubstantially smaller than the first and second radii R1 and R2 suchthat the superior portion 208 forms another substantially D-like shape.In other embodiments, the superior portion 208 can include greater orsmaller radii, more or less curved portions, and/or can have anothershape suitable for mating and at least substantially sealing twoendograft devices together within a blood vessel.

FIGS. 2D and 2E are cross-sectional top views of the superior portion208 of FIG. 2B being mated with a complementary superior portion 208 toform a sealed septum 220 in accordance with an embodiment of thetechnology. More specifically, FIG. 2D shows the superior portions 208being pressed toward one another by a force F. The force F can derivefrom the self-expansion of the superior portions 208 within the confinedspace of an aorta. As shown in FIG. 2D, the force F can cause thesuperior portions 208 to contact one another near the center of theirrespective convexly curved septal walls 214 and flatten the septal walls214. The apposition of the septal walls 214 can generate an outwardforce generally tangential to the septal walls 214 that can cause aslight outward bowing B near the interface of the outer and septal walls212 and 214.

As shown in FIG. 2E, the force F can continue to press the superiorportions 208 against one another until the convexly curved septal walls214 straighten to form the septum 220. The initial convexities of theseptal walls 214 can induce more pressure between the septal walls 214than straight septal walls (e.g., FIG. 2A) and promote an evendistribution of the force along the septum 220 to enhance the seal.Additionally, the outward bowing B can enhance the seal at the edges ofthe septal walls 214. The superior portions 208 shown in FIGS. 2A and 2Ccan be similarly joined to form the substantially straight septum 220.For example, the superior portion 208 shown in FIG. 2C can be pressedagainst a corresponding superior portion such that the relative forcesbetween the superior portions 208 substantially straighten the septalwalls 214 and corner sections 222 (e.g., approximately 60° to 90°between the outer and septal walls 112 and 114) to form the septum 220.In operation, the septum 220 can be at least substantially sealed toprevent fluids (e.g., blood) from flowing between the superior portions208.

1.3 Select Embodiments of Transition Portions

FIGS. 3A and 3B are isometric views of transition portions 324 ofendograft devices configured in accordance with embodiments of thetechnology. The transition portions 324 can promote laminar blood flowby gradually changing the size of the lumen 116 from the wider, superiorportion 108 to the narrower, inferior portion 110. Additionally, thetransition portions 324 can be configured to reduce the downforceexerted on the endograft devices 102 as blood flows through the lumen116.

More specifically, FIG. 3A is an isometric view of the endograft device102 described above with reference to FIGS. 1A and 1B. The endograftdevice 102 includes the transition portion 324 positioned between thesuperior portion 108 and the inferior portion 110. As shown in FIG. 3A,the transition portion 324 can be tapered to gradually narrow thecross-section of the lumen 116 and thereby reduce disruptions to theblood flow. The transition portion 324 can have a length L related tothe distance necessary to continue substantially laminar blood flowthrough the lumen 116. For example, in some embodiments, the length Lcan be 4 cm. In other embodiments, the length L can differ due to thegeometry of the endograft device 102, the rheologic characteristics ofthe blood flow, and/or other relevant factors in decreasing turbulentblood flow. In other embodiments, the transition portion 324 can besloped, stepped, and/or have another suitable shape that can decreasethe cross-section of the lumen 116 from the superior portion 108 to theinferior portion 110 without inducing turbulent blood flow.

FIG. 3B is an isometric view of an endograft device 302 in accordancewith another embodiment of the technology. The endograft device 302 caninclude generally similar features as the endograft 102 shown in FIG.3A. However, the tapered transition portion 324 shown in FIG. 3B has amore gradual taper and a much greater length L than the transitionportion 324 shown in FIG. 3A. As shown in FIG. 3B, the taperedtransition portion 324 extends from the superior portion 108 to thesecond end portion 118 b such that the transition portion 324 definesthe inferior portion 110 (not visible). Accordingly, the taperedtransition portion 324 can steadily decrease the cross-section of thelumen 116 to facilitate laminar blood flow through the lumen 116. Thegradual taper of the transition portion 324 may, however, cause theendograft device 302 to migrate in the direction of blood flow more thanthe more aggressive taper of the transition portion 324 shown in FIG.3A. Accordingly, the length L and angle of the tapered transitionportion 324 can be optimized to mitigate migration of the endograftdevice 302 without inducing undo turbulent blood flow. In otherembodiments, the transition portion 324 can optimize the geometry of adifferent shape (e.g., stepped) to maintain laminar blood flow andmitigate migration of the endograft device 302.

2. Endograft System Components

2.1 Integrated Frames

FIGS. 4A and 4B are side views of the integrated frame 104 describedwith reference to FIGS. 1A and 1B in an expanded configuration (FIG. 4A)and a low-profile configuration (FIG. 4B) in accordance with anembodiment of the technology. As discussed above, the frame 104 includesthe superior portion 108, the inferior portion 110, and the exposed endportions 118. In some embodiments, the smallest radius of the outer wall112 of each superior portion 108 in the expanded configuration may notbe less than 10 mm (i.e., the smallest diameter of the superior portions108 of mated endograft devices 102 is more than 20 mm).

As shown FIGS. 4A and 4B, the frame 104 can be a braided structure madefrom one or more continuous, interwoven wires 426 that provide acontinuous, integrated support longitudinally along the length of theframe 104. For example, as shown in FIG. 4A, the wire 426 is braidedsuch that a first longitudinal segment L1 of the frame 104 supports anadjacent second longitudinal segment L2 of the frame 104. Accordingly,each area of the frame 104 influences the radial expansion orcontraction of an adjacent area of the frame. In some embodiments, theframe 104 is woven with one wire 426 that continuously crosses itselfalong the length of the frame 104. The intersections of the wire 426 maynot be welded or otherwise fixed together such that they remain unboundto increase the flexibility of the frame 104. In other embodiments, theframe 104 includes a plurality of wires 426 that can be interwovenand/or concentrically layered to form the frame 104. The frame 104, forexample, can include eight wires 426 in which several of the wires 426can end at intermediate points along the length of the frame 104. Such astaggered, multi-wire construction prevents the wire ends from weakeningthe frame 104 and/or from wearing on a subsequently attached cover(e.g., the cover 106 shown in FIGS. 1A and 1B). The number of wires 426can also vary at different sections along the length of the frame 104.For example, in one embodiment, the inferior portion 110 includes fewerwires 426 than the superior portion 108 such that the density or pitchof the wires 426 does not increase at inferior portion 110 and the frame104. This enables the inferior portion 110 to have a small diameter inthe constricted, low-profile configuration (FIG. 4B).

As shown in FIG. 4A, the wires 426 can form a loop 428 at one endportion 118 to reverse direction and continue weaving along the lengthof the frame 104 toward the opposite end portion 118. The optimal numberof loops 428 at each end portion 118 can be associated with the diameterof the wires 426. Too few loops 428 can decrease the strength at the endportions 118 of the contracted frame 104 shown in FIG. 4A. Too manyloops 428 can increase the profile of the extended frame 424 shown inFIG. 4B, and can also cause difficulty attaching the cover. A wire 426with a diameter of 0.008 inch, for example, may have an optimal numberof ten to twelve loops 428 (five to six at each end portion 118),whereas a wire 426 with a diameter of 0.009 inch may have an optimalnumber of twelve to fourteen loops 428. In other embodiments, the wires426 can include more or less loops 428 to optimize characteristics ofthe frame 104. Additionally, the degree of curvature of each of theloops 428 can impact the durability of the wires 426. For example,tightly wound loops 428 with high degrees of curvature are subject tofatigue and failure at the end portions 118 because of the stressinduced upon constriction. Therefore, in some embodiments, the degree ofcurvature of the loops 428 can be the least degree of curvaturepermissible for the optimal number of loops 428.

In the expanded configuration shown in FIG. 4A, the wires 426 can crossat a braid angle θ selected to mitigate kinking and provide adequateextension/constriction. Lower braid angles θ can reduce or eliminatekinking of the wires 426 when the frame 104 is flexed or bent. Forexample, a braid angle θ of less than 45° allows the frame 104 to bendwith smaller radii of curvature without substantial reduction of itscross-sectional area along the length of the frame 104. Therefore, aframe 104 with a braid angle θ of less than 45° can be flexed and bentwithin the anatomy (e.g., the aorta) without restricting blood flowthrough the frame 104. Additionally, lower braid angles θ can increasethe outward spring force (i.e., the inherent force within the frame 104that self-expands the frame 104 to the expanded configuration) and hoopstrength (i.e., the radial strength of the frame 104 that restrictskinking and maintains the expanded configuration) of the frame 104.Therefore, braid angles θ of not more than 45° can also provide anadvantageous increase in the strength and corresponding durability ofthe frame 104.

Lower braid angles θ, however, can also adversely affect the extensionand constriction of the frame 104 in the low-profile configuration shownin FIG. 4B. For example, extension and constriction can be negativelyimpacted at braid angles θ of less than 30°. Therefore, in someembodiments, the frame 104 can include a braid angle θ between 30° and45° that promotes kink resistance and frame strength, while alsomaintaining extension and constriction abilities necessary for thelow-profile configuration. In other embodiments, the optimal braid angleθ can be higher or lower.

In some embodiments in accordance with the technology, the braid angle θcan vary along the length of the frame 104 to vary kink resistance,outward spring force, hoop strength, and extension properties atdifferent portions of the frame 104. For example, the braid angle θ canbe higher at the superior portion 108 (e.g., 40°) such that the superiorportion 108 can extend and constrict into the low-profile configuration,and the braid angle θ can be lower at the inferior portion 110 (e.g.,30°) to provide kink resistance where the frame 104 is most likely tobend (e.g., within the aneurysmal sac and toward the iliac arteries).The smaller braid angle θ at the inferior portion 110 may not adverselyaffect the profile of the frame 104 because the inferior portion 110need not constrict as much as the superior portion 108 to reach thedesired low-profile configuration. In other embodiments, the braid angleθ of the frame 104 may vary in another way.

The wires 426 can have a diameter sufficient to support the frame 104while still providing substantial flexibility for the frame 104. Thediameter of the wires 426 can be selected to attain a desiredcross-sectional dimension in the low-profile configuration, a desiredoutward spring force to self-expand to the expanded configuration, and adesired hoop strength to support the frame 104 in the expandedconfiguration. For example, in some embodiments, the wires 426 can havea diameter from approximately 0.007 inch to approximately 0.014 inch. Inspecific embodiments, the wires have a diameter from approximately 0.011inch to 0.013 inch. In other embodiments, the wires 426 can have asmaller diameter, a greater diameter, and/or the diameter of the wires426 can vary along the length of the frame 104. For example, in oneembodiment, the wires 426 can have a greater diameter at the superiorportion 108 than at the inferior portion 110 such that the wires 426 ofthe superior portion 108 have a outward spring force and greater hoopstrength where the first and second endograft devices mate (e.g., at theseptal walls 114) and the increased density of wires 426 at the inferiorportion 110 does not negatively impact the flexibility of the frame 104.

The frame 104 may be constructed from a variety of resilient metallicmaterials, polymeric materials (e.g., polyethylenes, polypropylenes,Nylons, PTFEs, and the like), and composites of materials. For example,the wires 426 can be made from biocompatible stainless steels, highlyelastic metallic alloys, and biocompatible shape setting materials thatexhibit shape memory properties. In some embodiments, for example, thewire 426 can be made from a shape setting alloy, such as Nitinol, thathas a preferred or native configuration. For example, a Nitinolstructure can be deformed or constrained into a secondary configuration,but upon release from the constraint, the structure returns toward itsnative configuration with high fidelity. Accordingly, a frame 104 madefrom Nitinol wires 426 can reliably self-expand from the low-profileconfiguration the expanded configuration (i.e., its nativeconfiguration).

For endovascular delivery of a device (e.g., the endograft devices 102shown in FIGS. 1A and 1B), the frame 104 is extended to constrict theframe 104 into a low-profile configuration in which the frame 104 can beloaded into a delivery device. The braid angle θ of the wires 426 canfacilitate significant extension of the frame 104 to produce a slenderprofile during delivery as described above, and yet the interwovencharacteristic of the braid restricts over extension. Thisextension-constriction functionality of the frame 104 allows the frame104 to have variable diameters (e.g., the diameter of the superiorportion 108 compared to the diameter of the inferior portion 11) usingthe same number of wires 426 on each portion of the frame 104 such thatthe frame 104 has a low introduction profile (e.g., diameter) along thelength of the frame 104. The frame 104 can also include an optimalnumber of loops 428 at each end portion 118 such that the loops 428 donot increase the profile of the frame 104 upon full extension.

At a target site (e.g., above an aneurysm), the frame 104 self-expandsto the expanded configuration shown in FIG. 4A as it is removed from thedelivery device. The braid angle θ can be adjusted to change the outwardspring force and hoop strength of the expanded frame 104 as explainedabove. In some circumstances, the endograft device may need to berepositioned after being partially deployed. The frame 104 is wellsuited for such repositioning because the loops 428 and the continuous,interwoven wires 426 can simplify recapture of the frame 104 and allowfor constriction after expansion to correctly reposition the endograftdevice. Additionally, portions of the frame 104 can remain exposed(e.g., the end portions 118) to encourage cell ingrowth for securelyanchoring the frame 104 to the arterial walls. Moreover, as described inmore detail below, the interwoven wires 426 of the braided frame 104 canprovide a continuous longitudinal support along the length of the frame104 such that the frame 104 can be staggered and free end portions cansupport themselves. The frame 104 can also facilitate attachment toother endograft devices. For example, the frame 104 can interlace withanother interwoven wire 426 of a supra-renal endograft.

Once deployed across the aneurysm, the frame 104 can also accommodatedisparate anatomies and morphologies. In several patients, theaneurysmal sac extends at an angle with respect to the neck of theaneurysm. Because the frame 104 can have a braid angle θ that preventskinking, the frame 104 can bend and flex without kinking to accommodateangulated aneurysmal sacs without restricting blood flow. Additionally,the unbound, woven wires 426 give the frame 104 a radial elasticity suchthat the frame 104 mimics the changes in the shape and morphology of theaorta without hindering the interface or seal between the endograftdevice and the vessel wall. For example, the frame 404 can constrict andexpand to maintain the seal when pressure and other conditions alter thevasculature of the aorta. Moreover, the woven wires 426 inherentlygenerate a spring force that biases the frame 104 toward a substantiallystraight trajectory within an aneurysmal sac and thereby limitsmigration of the endograft device.

In addition, the constant outward spring force and hoop strength of thebraided frame 104 can be adjusted by changing the braid angle θ and/orthe diameter of the wires 426. This allows the formation of largediameter frames 104 without a significant change in the low-profilecross-sectional dimensions. Additionally, this feature allows the frames104 to contract to a much smaller introduction profiles (e.g.,diameters) compared to standard Z-frames or M-frames because thestandard Z-frames and M-frames tend to require more wire and thereforelarger introduction profiles to maintain a constant outward spring forceand hoop strength.

2.2 Covers

FIGS. 5A-C are views of a cover being extended from an expandedconfiguration (FIG. 5A) to a low-profile configuration (FIG. 5C) inaccordance with embodiments of the technology. More specifically, FIG.5A is a side view of the cover 106 described above with reference toFIGS. 1A and 1B in the expanded configuration. The cover 106 can includea plurality of circumferential ribs 530 such that the cover 106 has anundulating profile. As shown in FIG. 5A, the individual ribs 530 canhave a substantially triangular shape with an apex 533. In otherembodiments, the individual ribs 530 have rounded edges, rectangularedges, and/or other suitable textures that can extend and contract.

The ribs 530 of one cover can mate with opposing ribs 530 of an opposingcover and interface with vessel walls to enhance the seal and fixationbetween endograft devices in an endograft system (e.g., the endograftdevices 102 of the endograft system 100 shown in FIGS. 1A and 1B) andbetween the endograft devices and the arterial walls. For example, theapices 533 of the ribs 530 at the septal wall 114 of the superiorportion 108 of one endograft device can interface or mate with thetroughs of the corresponding ribs 530 on a cover of an opposingendograft device. Additionally, the ribs 530 at the outer wall 112 cancontact the arterial walls in a manner that at least substantially sealsthem together. The ribs 530 can also allow the cover 106 to flex andbend without wrinkling in situ. In some embodiments, the ribs 530 can beat only selected portions of the cover 106 (e.g., the septal wall 114).In other embodiments, the ribs 530 can have different shapes and/orgeometries on different portions of the cover 106. For example, theapices 533 of the ribs 530 can have a first height on the superiorportion 108 to enhance sealing forces between the endograft devices anda second height less than the first height at the inferior portion 110to allow the cover 106 to freely flex and bend to accommodate theanatomy.

The ribs 530 change with the expansion and contraction of the cover 106.As shown in FIG. 5A, the apices 533 of the ribs 530 protrude to themaximal extent in the expanded configuration. Referring to FIG. 5B, asthe cover 106 extends, the ribs 530 also extend and constrict. When thecover 106 is fully extended in the low-profile configuration shown FIG.5C, the ribs 530 are completely elongated and constricted. In someembodiments, the size of each rib 530 can be predetermined to ensure theribs 530 are completely flattened in the low-profile configuration andproject radially outwardly to interface with adjacent surfaces in theexpanded configuration. Accordingly, the ribs 530 do not limit themobility of the endograft device as it is delivered to the aorta in thelow-profile configuration.

Additionally, as shown in FIGS. 5A-C, the cover 106 can includezigzagged edges at a superior terminus 531 a and an inferior terminus531 b of the cover 106. The zigzagged termini 531 can facilitatesubstantially seamless attachment between the cover 106 and anintegrated frame (e.g., the frame 104 shown in FIGS. 4A and 4B). Forexample, in some embodiments, the zigzagged termini 531 can correspondto the braid angle θ of interwoven wires. The zigzagged termini 531generally prevent the cover 106 from wrinkling or bunching at first andsecond end portions (e.g., the first and second end portions 118 a and118 b shown in FIGS. 4A and 4B) when the cover 106 and the frame areconstricted. In other embodiments, the superior and inferior termini 531a and 531 b can be scalloped, straight, and/or have another suitableshape that facilitates attachment and/or limits wrinkling.

The cover 106 can be made from a substantially impermeable,biocompatible, and flexible material. For example, the cover 106 can bemade from synthetic polymers, polyurethanes, silicone materials,polyurethane/silicone combinations, rubber materials, woven andnon-woven fabrics such as Dacron®, fluoropolymer compositions such as apolytetrafluoroethylene (PTFE) materials, expanded PTFE materials(ePTFE) such as TEFLON®, GORE-TEX®, SOFTFORM®, IMPRA®, and/or othersuitable materials. Additionally, in some embodiments, the cover 106 canbe made from a material that is sufficiently porous to permit ingrowthof endothelial cells. Such a porous material can provide more secureanchorages of endograft devices and potentially reduce flow resistance,sheer forces, and leakage of blood around the endograft devices.

In some embodiments in accordance with the technology, the cover 106 mayalso include drug-eluting coatings or implants. For example, the cover106 can be coated and/or imbedded with a slow-releasing drug that canblock cell proliferation, promote reendothelialization of the aneurysm,and/or otherwise medicate the aneurysmal region. Suitable drugs caninclude calcium, proteins, mast cell inhibitors, and/or other suitablemedicines that encourage beneficial changes at the aneurysmal region.

In accordance with other embodiments of the technology, the cover 106can be eliminated in favor of one or more layers of a coating material(shown and described in more detail with reference to FIGS. 17A-E). Thecoating layer can be made from a biocompatible synthetic polymer, suchas PTFE. The coating layer can be placed on the interior of anintegrated frame (e.g., the frame 104 shown in FIGS. 4A and 4B), theexterior of the frame, and/or interwoven throughout the frame. Like thecover 106, the coating layers can encase the frame to form a lumen(e.g., the lumen 116 shown in FIGS. 1A and 1B). Additionally, thecoating can have a selected porosity that encourages tissue ingrowth.

2.3 Integrated Frame and Cover

FIGS. 6A and 6B are cross-sectional views of the endograft device 102 ofFIGS. 1A and 1B in a low-profile configuration and an expandedconfiguration, respectively, in accordance with embodiments of thetechnology. As shown in FIGS. 6A and 6B, the cover 106 can be attachedto the exterior of the frame 104 at one or more attachment areas 632(identified individually as a first attachment area 632 a and a secondattachment area 632 b). The attachment areas 632 can have sutures,adhesives, welds, and/or other suitable fasteners that discretely holdthe cover 106 to the frame 104 at the attachment areas 632.

In the embodiment shown in FIGS. 6A and 6B, the endograft device 102 hasattachment areas 632 at only the superior and inferior termini 531 a and531 b of the cover 106 such that the remainder of the cover 106 betweenthe attachment areas 632 is not attached directly the frame 104. As aresult, the frame 104 and the cover 106 can fully extend and constrictas shown in FIG. 6A without interfering with one another. For example,in the low-profile configuration shown in FIG. 6A, the frame 104 doesnot directly pull the central portion of the cover 106 downward andlongitudinally with the frame 104 such that the ribs 530 can stretchuniformly along the length of the cover 106 to accommodate fullextension of the frame 104. Similarly, the intermediate portions of thecover 106 do not hinder the extension or constriction of the frame 104.Fewer attachments areas 632 can also limit the potential for fatigue andundesirable porosity that may arise at the attachment areas 632, such asfrom needle pricks and other fastening mechanisms that puncture thecover 106.

As shown in FIG. 6B, the cover 106 can substantially conform to theshape of the frame 104 when they are in the expanded configuration.Proper alignment between the cover 106 and the frame 104 prevents thecover 106 from adversely affecting constriction and expansion. Forexample, alignment between the cover 106 and the frame 104 at thesuperior and transition portions 108 and 324, respectively, ensures theframe 104 can expand properly and generate the force necessary to matewith a superior portion of an opposing endograft device. Additionally,in some embodiments, the cover 106 is sized to restrict the expansionand corresponding contraction of the frame 104.

Attaching the cover 106 to the exterior of the frame 104 as shown inFIGS. 6A and 6B can provide a plurality of benefits for the endograftdevice 102. For example, unlike endograft devices with internal coversthat must fold within a frame during delivery, the exterior cover 106does not inhibit constriction of the frame 104 (e.g., FIG. 6A). In theexpanded configuration, the exterior the cover 106 does not bunch orwrinkle within the frame 104, and thus does not cause thromboticproblems within the lumen 116. Additionally, unlike more rigid Z-stents,the flexibility of the frame 104 can prevent abrasive rubbing anddeterioration of the cover 106 in the expanded configuration (e.g., FIG.6B). The exterior attachment of the cover 106 can also prevent overexpansion of the frame 104.

2.4 Alignment Aids

FIGS. 7A and 7B are isometric views of endograft devices 702 inaccordance with additional embodiments of the technology. The endograftdevices 702 can have generally similar features as the endograft devices102 shown in FIGS. 1A and 1B. Additionally, the endograft devices 702can include alignment aids 734 that are visible under imaging systems(e.g., X-rays) to facilitate accurate positioning and subsequentmonitoring of the endograft devices 702 in the vasculature.

FIG. 7A is a partial cut-away isometric view of the endograft device 7-2showing an alignment aid 734 in accordance with an embodiment of thetechnology. As shown in FIG. 7A, the alignment aid 734 can extenddiagonally along the septal wall 114 of the frame 104 to indicate theposition of the septal wall 114 relative to the endograft device 702.The alignment aid 734 can thus provide an indication of the rotationalorientation and axial location of the endograft device 702 such thatduring deployment opposing septal walls 114 can be properly aligned andmated with one another. Additionally, as shown in the embodiment in FIG.7A, the alignment aid 734 can terminate at the superior terminus 531 aof the cover 106 to indicate where the first end portion 118 a begins.Thus, the alignment aid 734 provides a definitive indicator to ensurethat the cover 106 does not block transverse flow (e.g., from the aortato the renal arteries). In other embodiments, the alignment aids 734 maybe positioned elsewhere along the endograft device 702 to providespatial location and orientation that can aid delivery and deployment ofthe endograft device 702.

The alignment aid 734 can be made from radiopaque and/or fluoroscopicmaterials, such as tantalum, platinum, gold, and/or other materials thatare visible under an imaging system (e.g., X-rays). For example, asshown in FIG. 7A, the alignment aid 734 is made from a radiopaque wire(e.g., tantalum) wound around a segment of the frame 104. In anotherembodiment, a radiopaque composition is applied to the frame 104 and/orincorporated in the septal walls 114 of the cover 106.

FIG. 7B shows the first and second endograft devices 702 mated togetherusing the alignment aids 734 in accordance with an embodiment of thetechnology. As shown in FIG. 7B, the alignment aids 734 on the first andsecond endograft devices 702 a and 702 b are symmetrical such that whenthe endograft devices 702 are correctly oriented and the septal walls114 oppose one another, the alignment aids 734 can intersect to form an“X” indicator. In other embodiments, the intersection of the alignmentaids 734 forms other characters, numbers, and/or symbols that indicatethe rotational orientation and longitudinal location of the endograftdevices 702. In further embodiments, the alignment aids 734 can beapplied to different portions of the septal wall (e.g., the cover 102)and/or the outer wall 112. In still further embodiments, the endograftdevices 702 include a plurality of alignment aids 734 to distinguishdifferent portions of the endograft devices 702 and further aidrotational and/or other orientation. For example, in some embodiments,the inferior portions 110 include alignment aids 734 that differentiatethe inferior portions 110 of the first and second endograft devices 702.

2.5 Anchors

FIGS. 8A and 8B are isometric views of endograft devices 802 configuredin accordance with additional embodiments of the technology. Theendograft devices 802 can include generally similar features as theendograft devices 102 shown in FIGS. 1A and 1B. Additionally, theendograft devices 802 can include one or more anchors 836 that projectoutwardly from the frame 104 and/or cover 106 to engage the interiorsurfaces of arterial walls. The anchors 836 can be barbs, hooks, and orother shapes that can penetrate into the arterial walls. For example, asshown in FIG. 8A, the anchors 836 can be “V” shaped projections. In someembodiments, the anchors 836 eventually become embedded in cell growthon the interior surface of the arterial wall. In operation, the anchors836 resist migration of the endograft devices 802 within the artery andreduce the likelihood of endoleaks between the outer wall 112 and thearterial wall.

In an embodiment shown in FIGS. 8A and 8B, the anchors 836 project fromthe outer walls 112 to secure the superior portions 108 to the aorta. Inother embodiments, additional anchors 836 can project from the secondend portions 118 b to secure the inferior portions 110 to the iliacarteries. The anchors 836 can also protrude from the septal walls 114,extend through the lumen 116, and project outward beyond the outer wall112 to enhance the strength of the engagement. The anchors generallyproject inferiorly such that downward forces applied to the endograftdevices 802 (e.g., blood flow) drive the anchors 836 further into thearterial walls.

In one embodiment in accordance with the technology, the anchors 836 areseparate elements that are attached to the frame 104. For example, inthe embodiment shown in FIG. 8A, the anchors 836 are small barbs orwires that are fastened to the frame 104 by winding another wire (e.g.,a Nitinol wire) around the anchors 836 and the adjacent wire 426 of thebraid. In other embodiments, the anchors 326 are integrally formed withthe wire 426 used in the braid of the frame 104. For example, as shownin FIG. 8B, the anchors 836 are woven into the outer wall 112 of theframe 104. The interwoven anchors 836 can be deployed (i.e., projectoutwardly) when the frame 104 expands and can retract when the frame 104constricts. Accordingly, the interwoven anchors 836 do not inhibitmovement of the endograft device 802 during delivery in the low-profileconfiguration. In other embodiments, the anchors 836 can be attached toa different portion of the endograft device 802 (e.g., the cover 106).

The anchors 836 can be made from resilient metallic materials, polymericmaterials (e.g., polyethylenes, polypropylenes, Nylons, PTFEs), and/orother suitable materials that can anchor the endograft devices 802 toarterial walls. For example, the interwoven anchors 836 shown in FIG. 8Bcan be made from Nitinol wire 426 that comprises the frame 104.

3.Methods of Implementation and Assembled Endograft Systems

Described below are methods of deploying and assembling modularendograft systems across an aneurysm in accordance with embodiments ofthe technology. The associated Figures (i.e., FIGS. 9A, 9B, 11-13C and15A-16) include schematic representations of an abdominal portion of anaorta. More specifically, FIG. 9A shows an aneurysm 50 located along aninfrarenal portion of the aorta 52, which is the most common site of anAAA. A right or first renal artery 54 a and a left or second renalartery 54 b stem from the aorta 52. The region of the aorta 52 superiorto the aneurysm 50 and inferior to the renal arteries 54 is the aorticneck 60. The distal end portion of the aorta 52 bifurcates into commoniliac arteries 56 (identified individually as a first iliac artery 56 aand a second iliac artery 56 b), and the internal iliac arteries 58(identified individually as a first internal iliac artery 58 a and asecond internal iliac artery 58 b) branch from the common iliac arteries56. Other arteries and structures proximate to the abdominal portion ofthe aorta 52 have been removed for clarity.

3.1 Modular Endograft Systems

FIGS. 9A and 9B are schematic views of the two-part modular endograftsystem 100 described above being deployed across the aneurysm 50 inaccordance with an embodiment of the technology. FIG. 9A shows adelivery system 40 for implanting the first and second endograft devices102 a and 102 b. The delivery system can include a first catheter 42 a,a first guidewire 44 a associated with the first catheter 42 a, a secondcatheter 42 b, and a second guidewire 44 b associated with the secondcatheter 42 b. Each endograft device 102 (FIG. 9B) can be extended tothe low-profile configuration and loaded into the corresponding catheter42. Because the endograft devices 102 are delivered separately, thesizes of the catheters 42 are not constrained by the system 100 as awhole. In some embodiments, for example, the low-profile configurationsof each endograft device 102 can fit within a 12 F catheter. In otherembodiments, the low-profile configuration of the endograft devices 102can fit within differently sized catheters 42.

During deployment, the first catheter 42 a and the first guidewire 44 aare inserted percutaneously into a blood vessel (e.g., a femoral artery;not shown). With the aid of imaging systems, the first guidewire 44 a isendoluminally navigated through the vasculature, up the first iliacartery 56 a, and to a location superior to a target site T above theaneurysm 50. The first catheter 42 a is then passed through thevasculature along the first guidewire 44 a to the target site T. Using agenerally similar method, the second guidewire 44 b and the secondcatheter 42 b are delivered through the second iliac artery 56 b to thetarget site T. The first and second endograft devices 102 a and 102 bcan be delivered simultaneously or in succession.

The endograft devices 102 can be urged out of the distal ends of thecatheters 42 at the target site T by withdrawing the catheters 42proximally while holding the endograft devices 102 in place usingpushers or other suitable endovascular instruments. Alternatively, theendograft devices 102 can be pushed distally while holding the catheters42 in place. Upon release, the endograft devices 102 self-expand to theexpanded configuration shown in FIG. 9B. The guidewires 44 generallyremain in place to facilitate adjusting the endograft devices 102. Thiseliminates the need to cannulate either of the endograft devices 102.

Each endograft device 102 can be positioned at its desired locationindependently of the other endograft device 102 while the endograftdevices 102 are in, or at least partially within, the catheters 42. Forexample, in the embodiment illustrated in FIG. 9B, the superior portions108 contact the aortic neck 60 at the same level, and the inferiorportions 110 extend through the aneurysm 50 to their respective iliacarteries 56. More specifically, the inherent hoop force of the frame 104caused by the constant outward spring force of the braid at leastsubstantially seals (a) the covers 106 at the outer walls 112 againstthe aortic neck 60 and (b) the septal walls 114 to each other to formthe septum 120. The inferior portions 110 extend through the aneurysm 50and can bend to enter the iliac arteries 56. The proximal portion of theinferior portions 110 contact the iliac arteries 56 and can form a sealtherebetween. The flexibility of the frame 104 prevents the endograftdevices 102 from kinking at the bend and restricting blood flow.Additionally, as shown in FIG. 9B, the spring force within the frame 104biases the inferior portions 110 to extend in a substantially straighttrajectory through the aneurysm 50. This inhibits migration of theinferior portions 110 to a side of the aneurysm 50 that could break thecontact and/or seal at the aortic neck 60. As described in more detailbelow, in other embodiments the endograft devices 102 can be positionedindependently at different elevations along the aortic neck 60.

As further shown in FIG. 9B, the endograft system 100 can includeextension units 937 (identified individually as a first extension unit937 a and a second extension unit 937 b) projecting distally from thesuperior termini 531 of the covers 106. The extension units 937 caninclude an extension frame 904 (not visible) and an extension cover 906at least generally similar to the frame 104 and the cover 106 of theendograft devices 102 described above. The extension units 937 can havea substantially similar shape as the superior portions 108 of theendograft devices (e.g., a D-like shape) such that the extension units937 can mate with the interior of at least a part of the superiorportions 108. For example, as shown in FIG. 9B, the extension covers 906can be positioned inferior to the renal arteries 54 within the frame 104such that the extension covers 906 can interface with the aortic neck 60and mate with one another to extend the septum 120 distally. Therefore,the extension units 937 can increase the fixation area and the sealingarea of the endograft devices 102 when the superior termini 531 of thecovers 106 of the endograft devices 102 are offset from the entrances ofthe renal arteries 54. For example, in some embodiments, the extensionunits 937 add approximately one inch of fixation structure and sealingarea to the endograft devices 102. In other embodiments, the inferiorportions 110 can also include extension units 937 that can affix and atleast substantially seal to the iliac arteries 56.

During deployment, the extension units 937 can be added to the system100 after the first and second endograft devices 102 are positionedwithin the aortic neck 60. With the aid of the delivery system 40, theextension units 937 can advance along the guidewires 44 and be deployedfrom the catheters 42 at desired positions within the first and secondframes 104 just inferior of the renal arteries. Upon deployment, theextension units 937 can self-expand via an inherent spring force in theextension frame 904 to an expanded configuration to contact and at leastsubstantially seal with the interior of the superior portions 108 of theendograft devices 102. As shown in FIG. 9B, the extension cover 906 caninterface with the first end portions 118 a of the frames 104 tostrengthen the seal therebetween. In other embodiments, the extensionunits 937 can connect and seal to the endograft devices 102 using othersuitable attachment methods. The extension units 937 can be positionedindependently such that they accommodate anatomical variations (e.g.staggered renal arteries). For example, a superior terminus of the firstextension unit 937 a can be longitudinally offset from a superiorterminus of the second extension units 937 b. Similarly, the inferiorportions 110 can include extension units 937 that increase the sealingarea with the iliac arteries 56.

In some embodiments, alignment aids, such as the alignment aids 734described with reference to FIGS. 7A and 7B, are used to rotationallyorient the endograft devices 102 and align the septal walls 114 duringdelivery. Additionally, to prevent migration and/or projection of thesystem while in situ, anchors, such as the anchors 836 described abovewith reference to FIGS. 8A and 8B, can be deployed from the outer walls112 to engage the arterial walls of the aortic neck 60 and/or from thesecond end portions 118 b to engage the arterial walls of the iliacarteries 56.

FIGS. 10A-11 show additional embodiments of implementing endograftsystems (e.g., the system 100) in which the superior portions 108 arelongitudinally offset from each other. For example, in some embodiments,the superior portions 108 are longitudinally offset by at least 5 mm.The features of the systems below allow one or both of the superiorportions 108 to be placed over transverse arteries to increase theavailable fixation structure and sealing area for the endograft devices102 without inhibiting blood flow.

FIG. 10A is an isometric view of the modular endograft system 100 inwhich the endograft devices 102 are staggered such that the superiorportion 108 of the first endograft device 102 a is above the superiorportion 108 of the second endograft device 102 b. The first end portion118 a of the second endograft device 102 b can prevent the unsupportedfree first end portion 118 a of the first endograft device 102 a fromsplaying outward into the blood flow in a manner that induces undoturbulence. Moreover, the interplay between the woven wires 426 of theframe 104 of the first endograft device 102 a restricts the outwardmovement of the first end portion 118 a of the first endograft device102 a and provides substantially continuous support along the length ofthe frame 104 such the free first end portion 118 a retainssubstantially the same shape as if it were supported. These featuresmaintain the generally straight or convex shape of the unsupportedseptal region of the first portion 118 a of the first endograft device102 a. Using shape-setting Nitinol wire 426 in the frame 104 can furtherfacilitate maintaining the shape of the unsupported portion of the frame104.

Compared to conventional devices that have a common height across thediameter of a vessel (e.g., the aorta), the staggered configurationshown in FIG. 10A allows one or both of the first end portions 118 a toextend over the entrance of the renal arteries to increase the availablestructure for fixing the endograft devices 102 to the vessel wall. Thestaggered configuration also increases the sealing area of thesuperiorly positioned first endograft device 102 a for anatomies havinga short aortic neck (e.g., less than 2 cm). Similarly, the second endportions 118 b can extend over the entrances of the internal iliacarteries to ensure the inferior portions 110 each have an adequatestructure for fixing and at least substantially sealing the inferiorportions 110 to the iliac arteries. To the extent migration occurs, theadditional sealing area between the endograft devices 102 and the vesselwalls will reduce the potential for leakage at the aortic neck.

FIG. 10B is an isometric view of a modular endograft system 1000configured in accordance with an additional embodiment of thetechnology. The system 1000 can have a first endograft device 1002 a anda second endograft device 1002 b that are generally similar to theendograft devices 102 described above. The covers 106 of the endograftdevices 1002 in FIG. 10B, however, extend to the distal ends of thesuperior portions 108. Additionally, the endograft devices 1002 furtherinclude fenestrations 1038 on the outer walls 112 of the superiorportions 108.

The fenestrations 1038 can be openings through the cover 106 that exposethe frame 104 and provide a channel through which blood can flow to andfrom transverse arteries. For example, the endograft devices 1002 can bepositioned independently and staggered such that the fenestration 1038of each endograft device 1002 is aligned with one of the left or rightrenal arteries. The fenestrations 1038 accordingly increase theavailable sealing area between the outer walls 112 and the arterialwalls because the superior portions 108 can be positioned independentlyover the renal arteries such that one endograft device 1002 does notneed to be limited to the elevation of the inferior renal artery. Thisprovides optimal placement for each endograft device 1002 within thevasculature without requiring customized devices. In other embodimentsin accordance with the technology, the endograft devices 1002 caninclude additional fenestrations 1038 to increase the available sealingarea without restricting blood flow. For example, the inferior portions110 can include fenestrations 1038 that allow the inferior portions 110to extend over the entrance of the internal iliac arteries.

FIG. 11A is a schematic view of the modular endograft system 100deployed across an aneurysm such that the superior portions 108 of theendograft devices 102 are staggered to accommodate for anatomicalvariations in the vasculature in a manner that takes advantage of theavailable structure for fixing the endograft devices 102 to arterialwalls and the available sealing area in the aortic neck 60. In theembodiment shown in FIG. 11A, for example, the left renal artery 54 b isinferior the right renal artery 54 a. The first endograft device 102 acan, therefore, also be positioned higher in the aorta 52 to utilize theavailable fixation and sealing areas on the ipsilateral side of theaortic neck 60 without having to be concerned about blocking theentrance of the left renal artery 54 b. The first end portion 118 a ofthe second endograft device 102 b can be positioned over the left renalartery 54 b without inhibiting blood flow to lengthen the structure forfixing the second endograft device 102 b to the arterial wall and matingthe septal walls 114 together. The longer fixation and sealing areasalong the outer wall 112 of the first endograft device 102 a and thelonger mating and sealing areas between the septal walls 114 canstrengthen the seals of the system 100 as a whole to reduce thelikelihood of endoleaks. Additionally, as shown in FIG. 11A, the system100 can be staggered to accommodate an anatomy with less fixation andsealing area in one of the iliac arteries 56.

FIG. 11B is a schematic view of the modular endograft system 1000 ofFIG. 10B deployed across the aneurysm 60. Similar to the configurationof the system 100 shown in FIG. 11A, the endograft devices 1002 arestaggered to accommodate for anatomical variations in the vasculature ina manner that takes advantage of the available anatomical structure forfixing and sealing the outer walls 112 of the endograft devices 102 tothe arterial walls in the aortic neck 60. As shown in FIG. 11B, forexample, the first endograft device 1002 a can be positioned superior tothe second endograft device 1002 b in the aortic neck 60 to utilize theavailable fixation and sealing area on the ipsilateral side of theaortic neck 60. The fenestrations 1038 can be placed independently atthe entrance of each renal artery 54 to increase the available fixationand sealing area in the aortic neck 60 and accommodate asymmetricalanatomies. Additionally, as further shown in FIG. 11B, the endograftdevices can include fenestrations 1038 at the inferior portions 110 thatcan be placed independently at the entrance of each internal iliacartery 58 to accommodate an anatomy with less sealing area in the iliacarteries 56. In other embodiments, the endograft devices 102 can includefenestrations 1038 to accommodate other anatomical variations.

FIG. 12 is a schematic view of the modular endograft system of FIGS. 9Aand 9B deployed across an angulated aneurysm in accordance with anadditional embodiment of the technology. The system 100 can accommodatethis anatomical abnormality because the endograft devices 102 areflexible. More specifically, the interwoven wires 426 of the frame 104are sufficiently flexibility to bend without kinking. Thus, the bentendograft devices 102 can maintain unrestricted flow through the lumens116. Accordingly, the system 100 can accommodate other anatomicalvariations that may require the endograft devices 102 to flex or bendwithout disturbing blood flow.

FIGS. 13A-C are schematic views of a four-part modular endograft 1300system (“system 1300”) being deployed across the aneurysm 50 inaccordance with an embodiment of the technology. The system 1300 caninclude generally similar features as the system 100 described withreference to FIGS. 9A and 9B. However, as shown in FIG. 13B, theinferior portions 110 of the endograft devices 102 terminate within theaneurysm 50. Therefore, as shown in FIG. 13C, the system 1300 furtherincludes separate limbs 1362 (identified individually as a first limb1362 a and a second limb 1362 b) that contact and substantially sealwith corresponding inferior portions 110 and extend into correspondingiliac arteries 56. The limbs 1362 can be generally similar to theinferior portions 110. For example, the limbs 1362 can include anintegrated frame 1304 and a cover 1306 generally similar to the frame104 and the cover 106 described above with reference to FIGS. 1A-6B. Asshown in FIG. 13C, the limbs 1362 self-expand within the interiorportions 110 to the expanded configuration and thereby the superiorportions of the limbs 1362 at least substantially seals to the proximalsection of the inferior portions 110. The length of the limbs 1362within the inferior portions 110 can be adjusted to increase theavailable structure for fixing and sealing the limbs 1362 to theendograft devices 102. Additionally, in some embodiments, the covers1306 of the limbs 1362 can include ribs, such as the ribs 530 describedabove with reference to FIGS. 5A-C, that interface with the interior ofthe frames 104 and the covers 106 at the inferior portions 110 toconnect and at least substantially seal the limbs 1362 to the inferiorportions 110. In other embodiments, the limbs 1362 can connect and atleast substantially seal to the exteriors of the inferior portions 110using anchors (e.g., the anchors 836 described with reference to FIGS.8A and 8B), self-constricting forces, and/or, other suitable attachmentand sealing methods. The limbs 1362 extend the lumens 116 of theendograft devices 102 to the iliac arteries 56 such that blood can flowthrough the system 1300 to bypass the aneurysm 50.

Referring to FIG. 13A, the delivery system 40 is shown within theabdominal portion of the aorta 52 before deploying the endograft system1300. The insertion of the delivery system 40 can be generally similaras described above with reference to FIG. 9A. However, as shown in FIG.13A, the first and second guidewires 44 a and 44 b can cross after theyenter the aneurysm 50 such that each catheter 42 extends from itsrespective iliac artery 54 to the contralateral side of the aorta 52.For example, the first catheter 42 a can be delivered from the firstiliac artery 56 a to the left side of the aorta 52 proximate to the leftrenal artery 54 b (Arrow D₁), and the second catheter 42 b can bedelivered from the second iliac artery 56 b to the right renal artery 54a (Arrow D₂). In other embodiments, such as in the deployment methoddescribed above with reference to FIGS. 9A and 9B, the guidewires 44 donot cross within the aneurysm 50.

Referring to FIG. 13B, after the first and second catheters 42 a and 42b are positioned in the aortic neck 60, they are pulled proximally todeploy the endograft devices 102 through the distal ends of thecatheters 42. The crossing catheters 42 and guidewires 44 deploy theendograft devices 102 on opposite sides of the aortic neck 60.

As shown in FIG. 13B, the inferior portions 110 of the endograft devices102 terminate within the aneurysm 50 and form a “gate.” In general,gates are considered undesirable because in conventional systems theymust be cannulated to deliver and deploy limbs that extend the endograftdevices into the iliac arteries 56. However, as shown in FIG. 13B, theguidewires 44 remain within the endograft devices 102 after they aredeployed; this eliminates the need for time-consuming cannulation of thegates because the inferior portions 110 of the endograft devices 102 arein effect pre-cannulated. Such pre-cannulated gates allow the limbs 1362to be delivered through the distal ends of the catheters 42 andconnected to the inferior portions 110 much faster and more accuratelythan conventional systems.

FIG. 13C shows the system 1300 after both limbs 1362 are connected tothe endograft devices 102. As shown in FIG. 13C, the delivery system 40can also be used to adjust the length of the limbs 1362 and the lengthof the fixation area between the limbs 1362 and the inferior portions110 in the direction of the arrows. In the embodiment shown in FIG. 13C,for example, the second limb 1362 b extends further into the inferiorportion 110 of the second endograft device 102 b such that the secondlimb 1362 b is effectively shorter than the first limb 1362 a. Thelength of the limbs 1362 can be adjusted to accommodate disparateanatomies of the iliac arteries 56, maximize the fixation and sealingareas of the limbs 1362, and/or otherwise optimize the position of thelimbs 1362. This is possible because, at least in part, the inferiorportions 110 of the endograft devices 102 can be relatively long toallow significant longitudinal leeway in positioning the limbs 1362while still providing adequate surface area to at least substantiallyseal the limbs 1362 to the inferior portions 110.

The four-part, two-wire system 1300 can easily accommodate anatomicalvariations without requiring customized components. For example, thesuperior portions 108 can be staggered to maximize the mating andsealing area of each outer wall 112 with the aortic walls. Additionally,each limb 1362 can be selected from a relatively small number ofdifferent lengths to extend a desired length within the iliac arteries56 that both adequately connects and substantially seals the limbs 1362to the arterial walls and does not block transverse arterial flow. Thelimbs 1362 can also be adjusted independently relative to the inferiorportions 110 to increase the available structure for fixing and sealingthe limbs 1362 and the inferior portions 110 together, and to shorten orlengthen the limbs 1362 within the iliac arteries 56. Additionally, thebraided structure of the frames 104 can decrease infolding of the covers106 such that the lengths of the frame 104 can be selected fromstandardized cross-sectional dimensions. Thus, the four-part system 1300can be highly customizable, but yet comprise standardized components.

3.2 Modular Endograft System with Aortic Cuff

FIGS. 14A and 14B are isometric views of a modular endograft system 1400(“system 1400” shown in FIG. 14B) configured in accordance withembodiments of the technology. More specifically, FIG. 14A is anisometric view of an aortic cuff 1464 for use with the endograft devices102 (FIG. 14B). The aortic cuff 1464 can include a sleeve 1466 and acuff frame 1468. As shown in FIG. 14A, the sleeve 1466 and the cuffframe 1468 can be separate components. In other embodiments, the sleeve1466 and the cuff frame 1468 can be formed integrally. The aortic cuff1464 can expand from a low-profile configuration having a firstcross-section to an expanded configuration (e.g., FIG. 14B) having asecond cross-section larger than the first cross-section. Thelow-profile configuration can be used during delivery of the aortic cuff1464 from which the cuff-device 1464 can self-expand to the expandedconfiguration in situ. The aortic cuff 1464 can be configured tointerface and substantially seal with an infrarenal portion of the aortasuperior to an aneurysm.

The sleeve 1466 can be attached to the interior and/or exterior of thecuff frame 1468 using suitable fastening methods. For example, as shownin FIG. 14B, the sleeve 1466 is positioned within the interior of thecuff frame 1468, and the ends of the sleeve 1466 extend over and arefixed to proximal and distal ends of the cuff frame 1468 using suitablefastening methods (e.g., stitching, gluing, welding, etc.). In someembodiments, the proximal and distal ends of the cuff frame 1468 can beflared, and the sleeve 1466 can wrap around the flared ends to theexterior of the cuff frame 1468 such that the attachment can be sealedby the arterial walls when the aortic cuff 1464 is expanded to theexpanded configuration in situ. The sleeve 1466 can have generallysimilar characteristics as the cover 106 described above. For example,the sleeve 1466 can be made from one or more substantially impermeablematerials, such as Dacron® and PTFE, and can include ribs that caninterface with arterial walls and/or endograft devices 102 (FIG. 14B).The cuff frame 1468 can have generally similar characteristics as theintegrated frame 104 described above. In other embodiments, the cuffframe 1468 can be made from individual zigzagged wire hoops like aZ-stent.

The sleeve 1466 and the cuff frame 1468 can have a substantiallycylindrical shape. In some embodiments, the aortic cuff 1464 can includetwo channels to support superior portions 108 of endograft devices 102(FIG. 14B). For example, the channels can be formed by stitching thefabric of the sleeve 1466 together to divide the interior of the aorticcuff 1464. Additionally, the sleeve 1466 and/or the cuff frame 1468 canhave flared proximal and distal ends to form a stronger seal withadjacent arterial walls.

Referring to FIG. 14B, the endograft devices 102 are deployed within theaortic cuff 1464 after the cuff 1464 has been at least substantiallysealed against the aortic neck 60. The superior portions 108 can matewith and substantially seal to the interior of the aortic cuff 1464. Theribs 530 of the cover 106 can interface with the interior surface of thesleeve 1466 to further strengthen the seal. Additionally, the integratedframe 104 can further improve the seal between the endograft devices 102and the aortic cuff 1464. For example, the cross-section of the frame104 in the expanded configuration can be slightly larger than aninterior cross-section of the aortic cuff 1464. As the endograft devices102 are deployed within the aortic cuff 1464, the radial forces from theexpansion of the endograft devices 102 can strengthen the sealtherebetween. Additionally, in some embodiments, the transition portion324 of the endograft devices can mate with a complementary taper withinthe aortic cuff 1464.

In some embodiments in accordance with the technology, the aortic cuff1464 can include alignment aids, such as the alignment aids 734described above with reference to FIGS. 7A and 7B, to facilitatepositioning the endograft devices 102 within the aortic cuff 1464. Forexample, the aortic cuff 1464 and the outer walls 112 of the endograftdevices 102 can include orthogonal alignment aids that intersect toindicate the endograft devices 102 are properly aligned within theaortic cuff 1464.

In additional embodiments, the aortic cuff 1464 can include anchors,such as the anchors 836 described above with reference to FIGS. 8A and8B, to secure the to secure the system 1400 in situ. For example, thecuff frame 1468 can include anchors that project radially outwardly andengage adjacent arterial walls.

FIGS. 15A and 15B are schematic views of a three-part modular endograftsystem 1500 (“system 1500”) being deployed across the aneurysm 50 inaccordance with an embodiment of the technology. The system 1500 caninclude the endograft devices 102 described with respect to the system100 and the aortic cuff 1464 described above with reference to FIGS. 14Aand 14B.

Referring to FIG. 15A, the delivery system 40 can be inserted using agenerally similar method as described above with reference to FIG. 9A.In the embodiment shown in FIG. 15A, however, the first catheter 42 aand the first guidewire 44 a can be inserted first to deliver the aorticcuff 1464 (FIG. 15B) to the target site T. The aortic cuff 1464 can bedeployed using a generally similar method as deploying the endograftdevices 102 described above with reference to FIGS. 9A and 9B. The firstguidewire 44 a can be used to adjust the aortic cuff 1464 to a desiredposition in the aortic neck 60.

As shown in FIG. 15B, the endograft devices 102 can be deployed withinthe aortic cuff 1464. The endograft devices 102 can be deployed using asubstantially similar method as described with reference to FIG. 9B. Forexample, the endograft devices 102 can be delivered through the firstand second catheters 42 and positioned independently within the aorticcuff 1464 using the guidewires 44. Similar to the method of deployingthe superior portions 108 directly against the arterial walls describedwith reference to FIGS. 9B and 13B, here the outer walls of the superiorportions 108 can at least partially interface with the interior surfaceof the aortic cuff 1464 such that the septal walls are aligned with eachother to form the septum 120 (not visible). In some embodiments inaccordance with the technology, the aortic cuff 1464 can includesections shaped to receive the endograft devices 102 and thereby easealignment. In further embodiments, the first endograft device 102 a canbe anchored or otherwise secured to the aortic cuff 1464 beforedeployment such that only the second endograft device 102 b must bepositioned within the aortic cuff 1464.

FIG. 16 is a schematic view of a modular endograft system 1600 (“system1600”) being deployed across the aneurysm 50 in accordance with anotherembodiment of the technology. The system 1600 can be deployed usinggenerally similar methods as the system 1500 described above withreference to FIGS. 15A and 15B. As shown in FIG. 16, however, thesuperior portions 108 project above the aortic cuff 1464 such that thefirst end portions 118 a provide additional structure for securing theendograft devices to the arterial walls of the aorta 52. Additionally,the inferior portions 110 of the endograft devices 102 terminate withinthe aneurysm 50. Therefore, the system 1600 further includes limbs (notshown), such as the limbs 1362 described above with reference to FIGS.13A-C, that connect to the inferior portions 110 and extend into theiliac arteries 56. The catheters 42 can be used to adjust the length ofthe limbs to accommodate differing anatomies of the iliac arteries 56and to maximize the fixation and sealing areas between the limbs and thearterial walls. Additionally, in some embodiments, the limbs canintersect (e.g., the limbs 1362 shown in FIG. 13C) to strengthen theseal at the aortic neck 60 and decrease the likelihood of endoleaks.Similar to the four-part system 1300 described above, the five-partsystem 1600 can accommodate anatomical variations without requiringcustomized components.

In the embodiments illustrated in FIGS. 9A, 9B, 11-13C, 15A, 15B and 16,the aneurysm 50 is shown in the infrarenal portion of the aorta 52because this is the most common site of an AAA. In other embodiments inaccordance with the technology, the modular endograft systems 100, 1000,1300, 1500 and 1600 can be deployed across aneurysms 50 at differentportions of the aorta 52 or in other vessels altogether. For example, insome embodiments, the aneurysm 50 can extend from the infrarenal portionof the aorta 52 into one or both of the common iliac arteries 56. Theinferior portions 110 or the limbs 1362 of the systems 100, 1000, 1300,1500 and 1600 can extend past the diseased, aneurysmal portion of theiliac arteries 56 without blocking blood flow to the internal iliacarteries 58. In other embodiments, the systems 100, 1000, 1300, 1500 and1600 can be deployed across aneurysms 50 located in the supra renalportion of the aorta 52 with the fenestrations 1038 and/or the first endportions 118 a positioned at the entrance of the renal arteries 54. Infurther embodiments, the systems described above can be deployed acrossaneurysms in other portions of the vasculature that benefit from the useof a bifurcated, bi-luminal modular endograft system that can beindependently positioned.

4. Methods of Manufacturing

4.1 Integrated Frame

Referring back to FIGS. 4A and 4B, the integrated frame 104 can be madeby weaving or braiding one continuous wire 426 in a pattern along acylindrical mandrel. In some embodiments, the wire 426 is woven with aone over and one under pattern. In other embodiments, the wire 426 iswoven with a two over and one under pattern, another integrated pattern,and/or a pattern that varies over the length of the frame 104. Theintersections of the wire 426 can remain unbound to increase flexibilityof the frame 104. The wire 426 can form the loops 428 to changedirection and continue the pattern of intersecting wires 426. Asdescribed above, the number of loops 428 at each end portion 118 and thebraid angle a can be selected based on the diameter of the wire 426 andthe desired properties of the frame 104.

The wire 426 can be removed from the mandrel after it is braided intothe frame 104 and formed into a desired shape (e.g., the endograftdevices 102 shown above). The frame 104 can then be heated to ashape-setting temperature specified for the wire material (e.g.,Nitinol), and subsequently quenched. Optionally, the frame 104 can beannealed to increase the strength of the frame 104. The mandrel can becylindrical or have the shape of the frame 104 such that the wire 426remains on the mandrel during heat treatment. In further embodiments,the frame 104 can be manufactured using other suitable methods forshaping resilient biocompatible materials.

4.2 Covers and Coatings

Referring to FIGS. 5A-C, the cover 106 can be made by shaping asubstantially non-permeable cover material, such as Dacron®, PTFE,and/or other suitable biocompatible materials. The cover 106 can beformed by first placing the cover material over a mandrel. The mandrelcan include thin grooves that can correspond to the desired geometry ofthe ribs 530 on the cover 106. A wire or thread can be wrapped over thecover material and into the grooves to corrugate the cover material. Thecover material can then be heated on the mandrel until the ribs 530 areformed and the cover 106 is substantially non-permeable. In someembodiments, the superior and inferior termini 531 a and 531 b of thecover 106 can be shaped to facilitate attaching the cover 106 to a frame(e.g. the frame 104 shown in FIGS. 4A and 4B) and prevent the cover 106from wrinkling at end portions (e.g., the end portions 118 shown inFIGS. 1A and 1B) during constriction. For example, the superior andinferior termini 531 a and 531 b can be zigzagged as shown in FIGS. 5Aand 5B, scalloped, or otherwise shaped to limit wrinkling of the coveron the frame.

In other embodiments in accordance with the technology, coating layerscan be used in place of or in conjunction with the cover 106. FIGS.17A-E are views of coating layers being applied to an integrated frame1704 (“frame 1704”) in accordance with embodiments of the technology.The frame 1704 has generally similar features as the frame 104 describedabove. For example, the frame 1704 can be made from the braided wire426.

Referring to FIG. 17A, the frame 1704 is positioned over a mandrel 80 inthe expanded configuration. As shown in FIG. 17A, a first coating layer1770 can be wrapped onto the frame 1704. The first coating layer 1770can be a single or double layer of unsintered tape that can beapproximately 0.0005″ thick and made from PTFE. In other embodiments,the first coating layer 1770 can have a different thickness and/or thefirst coating layer 1770 can be made from another suitable coatingmaterial.

Once the first coating layer 1770 is applied over the frame 1704, thefirst coating layer 1770 and the frame 1704 can be heated on the mandrel80 in an oven. For example, the first coating layer 1770 and the frame1704 can be heated for less than thirty minutes in a 370° C. oven. Afterheating, the coated frame 1704 is removed from the mandrel 80 andextended and contracted from the low-profile configuration to theexpanded configuration to ensure the first coating layer 1770 properlyadhered to the frame 1704 during heat treatment.

As shown in FIG. 17B, a second coating material 1772 is placed over anarrower, second mandrel 82. The second coating material 1772 can beextended a distance equivalent to the length of the frame 1704 in thelow-profile configuration. Referring to FIG. 17C, the second coatingmaterial 1772 is contracted to the length of the frame 1704 in theexpanded configuration. This contraction can form small ribs 1730 in thesecond coating material 1772. The ribs 1730 can be generally similar tothe ribs 530 described above with reference to FIGS. 5A-C, but they areon the interior of the frame 1704. The ribs 1730 prevent the secondcoating material 1772 from wrinkling or bunching when the subsequentlyattached frame 1704 flexes or bends and thereby reduce the likelihood ofthrombotic problems within the lumen.

As shown in FIG. 17D, the coated frame 1704 is then extended to thelow-profile configuration and placed over the extended second coatingmaterial 1772 on the second mandrel 82. Each diamond opening along theframe 1704 can be spot welded using a welding device 84. Then, the frame1704 is removed from the second mandrel 82 and extended and contractedfrom the low-profile configuration to the expanded configuration toensure that the first and second coating layers 1770 and 1772 haveadequately adhered to the frame 1704. Additionally, the proximal anddistal ends of the frame 1704 are verified to ensure that the first andsecond coating layers 1770 and 1772 have properly adhered to the frame1704. If necessary, tacking can be performed and the edges can betrimmed to form a dual coated endograft device 1702 shown in FIG. 17E.

From the foregoing, it will be appreciated that specific embodiments ofthe invention have been described herein for purposes of illustration,but that various modifications may be made without deviating from thespirit and scope of the technology. For example, the embodimentsillustrated in FIGS. 1A-16 include covers 106 that extend over theexterior of the integrated frames 104. However, other embodiments of thetechnology can include covers 106 that are attached to the interior ofthe integrated frame 104 and/or are formed integrally with the frame104. Certain aspects of the new technology described in the context ofparticular embodiments may be combined or eliminated in otherembodiments. For example, in the embodiments illustrated above, eachendograft device (e.g., 102, 1002) includes a singular lumen 116.However, the endograft devices can include additional lumens thattransverse, bisect, and/or otherwise communicate with the lumen 116 toaccommodate the vasculature. For example, the endograft devices caninclude lumens that extend into the renal arteries, the internal iliacarteries, and/or other arteries. Further, while advantages associatedwith certain embodiments of the technology have been described in thecontext of those embodiments, other embodiments may also exhibit suchadvantages, and not all embodiments need necessarily exhibit suchadvantages to fall within the scope of the technology. Accordingly, thedisclosure and associated technology can encompass other embodiments notexpressly shown or described herein.

1. A modular endograft system, comprising: a first guidewire; a firstendograft device positioned along the first guidewire, the firstendograft device having a first superior portion, a first inferiorportion, and a first lumen through the first superior and inferiorportions, and the first superior portion having a first outer wall and afirst septal wall; a first limb positioned along the first guidewire andcoupled to the first inferior portion of the first endograft device; asecond guidewire; a second endograft device positioned along the secondguidewire, the second endograft device having a second superior portion,a second inferior portion, and a second lumen through the secondsuperior and inferior portions, and the second superior portion having asecond outer wall and a second septal wall, wherein the first septalwall of the first endograft device presses against the second septalwall of the second endograft device; and a second limb positioned alongthe second guidewire and coupled to the second inferior portion of thesecond endograft device.
 2. The modular endograft system of claim 1,wherein: the first outer wall is convexly curved, and the first septalwall and first outer wall form a substantially D-shaped cross-section;and the second outer wall is convexly curved, and the second septal walland the second outer wall form a substantially D-shaped cross-section.3. The modular endograft system of claim 2, wherein: the first septalwall is convexly curved in a direction opposite the convex curvature ofthe first outer wall; and the second septal wall is convexly curved in adirection opposite the convex curvature of the second outer wall.
 4. Themodular endograft system of claim 2, wherein the first and second septalwalls are at least substantially straight and form a septum.
 5. Themodular endograft system of claim 2 wherein: the first and secondinferior portions of the first and second endograft devices have acircular cross-section; and the first and second limbs have circularcross-sections.
 6. The modular endograft system of claim 1 wherein: thefirst endograft device has an integrated first frame (“first frame”) anda first cover exterior of the first frame, wherein the first lumen iswithin the first cover, and wherein the first cover has a first superiorterminus and the first frame has a first end portion extending distallyfrom the first superior terminus of the first cover; and the secondendograft device has an integrated second frame (“second frame”) and asecond cover exterior of the second frame, wherein the second lumen iswithin the second cover, and wherein the second cover has a secondsuperior terminus and the second frame has a first end extendingdistally from the second superior terminus of the second cover.
 7. Themodular endograft device of claim 6, wherein the first and second frameseach include a superior terminus, an inferior terminus, and a continuouswire woven in a braid in which the wire crosses itself at a braid angle,and wherein the wire reverses direction at the superior terminus of theframe to form a first plurality of loops and reversing direction at theinferior terminus of the frame to form a second plurality of loops. 8.The modular endograft system of claim 7 wherein the wire is unboundwhere it crosses itself.
 9. The modular endograft device of claim 7wherein the braid angle is from approximately 30° to approximately 45°.10. The modular endograft device of claim 6, wherein: the first coverincludes a plurality of first ribs, the first ribs protruding radiallyfrom the first frame in an expanded configuration and being extendablelongitudinally in a low-profile configuration; the second cover includesa plurality of second ribs, the second ribs protruding radially from thesecond frame in an expanded configuration and being extendablelongitudinally in a low-profile configuration; and wherein the firstribs on the first septal wall interface with the second ribs at thesecond septal wall in the expanded configuration.
 11. The modularendograft device of claim 1 wherein: the first superior portion has across-sectional dimension of at least 20 mm in an expanded configurationand a cross-sectional dimension of at most 5 mm in a low-profileconfiguration; and the second superior portion has a cross-sectionaldimension of at least 20 mm in an expanded configuration and across-sectional dimension of at most 5 mm in a low-profileconfiguration.
 12. The modular endograft system of claim 1 wherein: thefirst endograft device includes a plurality of first ribs; the secondendograft device includes a plurality of second ribs; and the first ribsmate with the second ribs in an expanded configuration.
 13. The modularendograft system of claim 1 wherein the first and second limbs eachinclude a cover having a plurality of circumferential ribs protrudingradially from the cover, the ribs of the first limb contacting aninterior of the first inferior portion, and the ribs of the second limbcontact an interior of the second inferior portion.
 14. The modularendograft system of claim 1, further comprising: a first alignment aidat the first septal wall; a second alignment aid at the second septalwall, wherein the second alignment aid crosses the first alignment aidwhen the first and second septal walls are aligned; and wherein thefirst and second alignment aids comprise a radiopaque material.
 15. Amodular endograft system comprising: a first guidewire; a firstendograft device positioned along the first guidewire, the firstendograft device having a first superior portion, a first inferiorportion, a first braided frame, and a first lumen through the firstsuperior and inferior portions; a first limb positioned along the firstguidewire and coupled to the first inferior portion of the firstendograft device; a second guidewire; a second endograft devicepositioned along the second guidewire, the second endograft devicehaving a second superior portion, a second inferior portion, a secondbraided frame, and a second lumen through the second superior andinferior portions, wherein septal walls of the first and secondendograft devices press against one another to form a septum; and asecond limb positioned along the second guidewire and coupled to thesecond inferior portion of the second endograft device; and wherein thefirst and second braided frames are configured to have substantiallycontinuous longitudinal support along the superior and inferior portionsof the first and second endograft devices, respectively.
 16. The modularendograft system of claim 15 wherein the first and second braided framesare woven from a wire such that each longitudinal segment of each framesupports adjacent longitudinal segments along the length of each frame.17. The modular endograft system of claim 16 wherein each longitudinalsegment of the frame influences the radial expansion or contraction ofthe adjacent longitudinal segment of the frame.
 18. The modularendograft system of claim 15 wherein: the first and second superiorportions each include a convexly curved outer wall and a convexly curvedseptal wall, the outer walls having a first radius of curvature and theseptal walls having a second radius of curvature less than the firstradius of curvature such that the first and second superior portionshave a substantially D-like cross-sectional shape; and the first andsecond endograft devices expand via an inherent spring force such thatopposing forces between the first and second septal walls aresubstantially uniform along the septum.
 19. The modular endograft systemof claim 15 wherein the first endograft device has a first alignment aidand the second endograft device has a second alignment aid, and whereinthe first and second alignment aids are configured to indicate arotational orientation and a longitudinal position of the first andsecond endograft devices relative to each other.
 20. The modularendograft system of claim 15 wherein the first endograft device has afirst cover attached to a portion of the first frame, and the firstcover having a first opening, and wherein the first opening allows bloodto flow laterally relative to the first lumen.
 21. The modular endograftsystem of claim 15 wherein: the first superior portion has across-sectional dimension of at least 20 mm in an expanded configurationand a cross-sectional dimension of at most 5 mm in a low-profileconfiguration; and the second superior portion has a cross-sectionaldimension of at least 20 mm in an expanded configuration and across-sectional dimension of at most 5 mm in a low-profileconfiguration.
 22. The modular endograft system of claim 15 wherein: thefirst and second endograft devices include first and second covers,respectively, the first and second covers having a plurality ofcircumferential ribs that protrude radially; the first limb includes athird cover having a plurality of circumferential ribs that protruderadially; the second limb includes a fourth cover having a plurality ofcircumferential ribs that protrude radially; the third cover of thefirst limb contacts an interior of the first inferior portion of thefirst endograft device such that the ribs on the third cover interfacewith the ribs on the first cover of the first endograft device; and thefourth cover of the second limb contacts an interior of the secondinferior portion of the second endograft device such that the ribs onthe fourth cover interface with the ribs on the second cover of thesecond endograft device.
 23. The modular endograft device of claim 15wherein: the first endograft device includes a first transition portionbetween the first superior portion and the first inferior portion, thefirst transition portion tapering the first lumen from a firstcross-sectional dimension at the superior portion to a secondcross-sectional dimension less than the first cross-sectional dimensionat the inferior portion, wherein the transition portion is configured tomaintain substantially laminar blood flow through the first lumen in theexpanded configuration; and the second endograft device includes asecond transition portion between the second superior portion and thesecond inferior portion, the second transition portion tapering thesecond lumen from the first cross-sectional dimension at the secondsuperior portion to the second cross-sectional dimension at the secondinferior portion, wherein the second transition portion is configured tomaintain substantially laminar blood flow through the second lumen inthe expanded configuration.
 24. A method of treating an aneurysm in aprimary vessel at a location before a bifurcation into a first vesseland a second vessel, the method comprising: positioning a firstendograft device over a first guidewire relative to the aneurysm suchthat at least a segment of a first superior portion of the firstendograft device is positioned superior to the aneurysm and a firstinferior portion of the first endograft device extends only partiallythrough the aneurysm, the first superior portion having a convexlycurved first outer wall and a first septal wall; positioning a secondendograft device over a second guidewire relative to the aneurysm suchthat at least a segment of a second superior portion of the secondendograft device is positioned superior to the aneurysm and a secondinferior portion of the second endograft device extends only partiallythrough the aneurysm, the second superior portion having a convexlycurved second outer wall and a second septal wall, and wherein thesecond endograft device is positioned independently of positioning thefirst endograft device; deploying the first endograft device from afirst catheter and deploying the second endograft device from a secondcatheter such that the first and second septal walls press against eachother to form a septum between the first and second endograft devices;implanting a first limb over the first guidewire such that a distalportion of the first limb is coupled to the first inferior portion ofthe first endograft device and a proximal portion of the first limb isin the first vessel; and implanting a second limb over the secondguidewire such that a distal portion of the second limb is coupled tothe second inferior portion of the second endograft device and aproximal portion of the second limb is in the second vessel.
 25. Themethod of claim 24, wherein the first septal wall is convexly curved ina direction opposite the first outer wall and the second septal wall isconvexly curved in a direction opposite the second outer wall, andwherein deploying the first and second endograft devices comprisesurging the convexly curved first and second septal walls together. 26.The method of claim 25 wherein urging the convexly curved first andsecond septal walls together results in a more uniform distribution ofpressure between the first and second septal walls compared to straightfirst and second septal walls.
 27. The method of claim 24 whereinpositioning the first and second endograft devices comprises staggeringthe first superior portion of the first endograft device relative to thesecond superior portion of the second endograft device such that aportion of the first septal wall is positioned superior relative to adistal most terminus of the second septal wall.
 28. The method of claim24 wherein: the first catheter has a maximum cross-sectional dimensionof 5 mm and the first outer wall of the first superior portion of thefirst endograft device has a radius of curvature not less than 10 mmafter being deployed from the first catheter; and the second catheterhas a maximum cross-sectional dimension of 5 mm and the second outerwall of the second superior portion of the second endograft device has aradius of curvature not less than 10 mm after being deployed from thesecond catheter.
 29. The method of claim 24 wherein the first endograftdevice includes a first alignment aid at the first septal wall, whereinthe second endograft device includes a second alignment aid at thesecond septal wall, the first and second alignment aids comprising aradiopaque material, and wherein deploying the first and secondendograft devices further includes: radiographically positioning thefirst and second alignment aids such that the first and second alignmentaids oppose one another; viewing the first and second alignment aids inthe orthogonal plane; and crossing the first and second alignment aidssuch that the first and second septal walls form the septum.
 30. Themethod of claim 24 wherein the primary blood vessel includes a thirdblood vessel branching from the primary blood vessel before theaneurysm, and wherein: the first endograft device includes a frame, acover, and a lumen within the cover, wherein a superior end portion ofthe frame projects distally beyond a superior terminus of the cover; anddeploying the first and second endograft devices includes positioningthe distal end portion of the first endograft device at the third bloodvessel such that blood flows laterally through the distal end portionrelative to a longitudinal axis of the lumen.
 31. The method of claim 24wherein implanting the first and second limbs further comprises:positioning the distal portion of the first limb within the firstinferior portion and expanding the first limb via an inherent springforce in the second limb to contact an internal surface of the firstinferior portion; and positioning the distal portion of the second limbwithin the second inferior portion and expanding the second limb via aninherent spring force in the second limb to contact an internal surfaceof the second inferior portion.
 32. The method of claim 31 whereinpositioning the distal portions of the first and second limbs furthercomprises: adjusting the length of the first limb within the firstinferior portion such that the proximal portion of the second limbpresses against an interior the second vessel; and adjusting a length ofthe second limb within the second inferior portion such that theproximal portion of the second limb presses against an interior thesecond vessel.